Clinical Nutrition Assessment

The definitive FAO report replacing PDCAAS with the Digestible Indispensable Amino Acid Score (DIAAS). DIAAS uses true ileal digestibility rather than faecal digestibility, preventing overestimation of plant protein quality. Animal proteins (egg, dairy, meat) score ≥1.0; most plant proteins score 0.4–0.7, with legumes at 0.5–0.8. The report established DIAAS as the gold-standard metric for comparing protein sources used in nutrition counselling worldwide.

Compared DIAAS and PDCAAS scores for 34 protein sources using ileal digestibility data. PDCAAS routinely truncated scores at 1.0, masking superior quality of egg white and whey. Under DIAAS, whole egg scored 1.13, whey isolate 1.09, beef 1.05, soy isolate 0.90, and pea 0.82. This has direct implications for plant-based athletes who must consume 10–20% more total protein to meet indispensable amino acid requirements.

ESPEN expert group reviewed protein requirements in ageing populations, recommending 1.0–1.2 g/kg/day for healthy older adults and 1.2–1.5 g/kg/day with acute or chronic illness. Critically, leucine-rich, high-DIAAS proteins (dairy, egg, meat) are preferred over low-DIAAS plant sources in older adults where anabolic resistance demands maximal amino acid availability per gram consumed.

Seminal nitrogen balance study establishing that endurance athletes require 1.37 g protein/kg/day — 67% above the then-RDA — while strength athletes required 1.76 g/kg/day to achieve positive nitrogen balance. Demonstrated for the first time that exercise substantially elevates protein requirements beyond sedentary RDA values, underpinning modern sport nutrition targets.

Meta-analysis of 235 nitrogen balance estimates across 19 studies in healthy adults. Derived a safe protein intake of 0.83 g/kg/day for sedentary adults (EAR 0.66 g/kg/day). Critically noted that nitrogen balance studies systematically underestimate requirements due to adaptation to low intakes and measurement losses not captured in urine — a methodological limitation that supports higher real-world targets for active individuals.

Reviews stable isotope tracer methodology for measuring muscle protein synthesis (MPS) and breakdown (MPB) in humans. Whole-body protein turnover is ~250–300 g/day — far exceeding dietary intake — reflecting constant synthesis and degradation cycles. Net muscle protein accretion depends on MPS > MPB, a balance tipped by adequate leucine-containing protein intake and resistance exercise, providing the mechanistic basis for protein timing and distribution strategies.

Comprehensive review demonstrating that self-reported dietary intake substantially under-reports actual consumption: adults under-report energy intake by 12–54%, with greater under-reporting in higher-BMI individuals and for energy-dense foods. Self-reported protein was more accurate than calories. Digital food logging (apps with photo verification) reduces under-reporting versus paper records, supporting app-based diary tools as clinically preferable to recall-based methods.

Validated 24-hour diet records against the doubly labelled water (DLW) gold standard in 160 volunteers. Found 24-hour records underestimated energy intake by a mean 18% (range 6–40%). Protein tracking was most accurate (within 10%) due to lower social desirability bias around protein reporting compared to fats and sweets. Supports protein as the most reliably tracked macronutrient in food diaries.

Reviewed 22 studies examining dietary self-monitoring frequency and weight loss outcomes. Consistent finding: more frequent and complete self-monitoring correlated with greater weight loss (average 4.5 kg advantage vs. non-monitors at 6 months). Digital apps with barcode scanning and nutrient breakdowns outperformed paper journals for sustained logging adherence — directly validating the food diary approach used in this platform.